public class MergeTwoSortedList {
    public ListNode mergeTwoLists(ListNode l1, ListNode l2){
        if(l1==null)return l2;
        if(l2==null)return l1;
        if(l1.val<l2.val){
            l1.next=mergeTwoLists(l1.next,l2);
            return l1;
        }else{
            l2.next=mergeTwoLists(l1,l2.next);
            return l2;
        }

    }
}
